1. Field of the Invention
This invention relates to heat seal splicers for splicing film strips and in particular to an improvement in the splicing station for such splicers.
2. Description of the Prior Art.
Heat seal splicers for splicing film strips are well known in the art, one example being the splicer shown in U.S. Pat. No. 3,725,168. In such splicers, a length of heat activated splice tape is applied under heat and pressure to the ends of film to be spliced. The splice station includes a splice pad for supporting the ends of film to be spliced, a heated splice head for applying the splice tape under heat and pressure to the film ends, and a guide track for supporting and guiding the splice head. The heated splice head is moved along the guide track to the splice pad by means such as a pneumatic or hydraulic cylinder.
A slot is provided in the guide track, near the splice pad, through which lengths of the splice tape are advanced from a continuous supply. As the splice head is moved towards the splice pad, a portion of the splice head cooperates with the guide track to sever the length of splice tape from the supply. As the splice head continues its movement toward the splice pad, the heat activated splice tape is applied to the ends of the film to effect the splice. In order to effectively sever the splice tape and to insure proper alignment of the heated splice head with the splice pad, the splice head is continuously urged into contact with the guide track by means such as springs connected between the splice head and the guide track. Although it is desirable to have the splice head in tight contact with the guide track when the splice tape is being severed and when the splice is being made, contact with the guide track at other times results in undesirable heat sinking from the splice head into the guide track. Due to this heat sinking, the heating element in the splice head expends energy which is wasted in heating up the guide track. If the guide track becomes too hot, the slot through which the splice tape passes may prematurely activate the adhesive on the tape, resulting in the build-up of a gummy residue at the slot and eventual fouling of the splice tape advance.
This heat sinking phenomenon also results in a longer warm-up time when the splicer is first turned on since some of the energy used to heat up the splice head is dissipated into the guide track.
It was recognized by the inventor that the elimination of this heat sinking would permit the use of a lower power heating element in the splice head, would result in faster machine warm-up times, and would eliminate the problem of an accumulation of the heat activated adhesive on the splice tape slot in the guide track.